//线段测距,不是我写的,https://www.jianshu.com/p/4a97d3ed4a06
export default function measureLine() {

    let Cesium = this.Cesium;
    let viewer = this.viewer;
    // 取消双击事件-追踪该位置
    viewer.cesiumWidget.screenSpaceEventHandler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);

    let handler = new Cesium.ScreenSpaceEventHandler(viewer.scene._imageryLayerCollection);
    var positions = [];
    var poly = null;
    // var tooltip = document.getElementById("toolTip");
    var distance = 0;
    var cartesian = null;
    var floatingPoint;
    // tooltip.style.display = "block";

    handler.setInputAction(function (movement) {
        // tooltip.style.left = movement.endPosition.x + 3 + "px";
        // tooltip.style.top = movement.endPosition.y - 25 + "px";
        // tooltip.innerHTML = '<p>单击开始，右击结束</p>';
        // cartesian = viewer.scene.pickPosition(movement.endPosition);
        let ray = viewer.camera.getPickRay(movement.endPosition);
        cartesian = viewer.scene.globe.pick(ray, viewer.scene);
        //cartesian = viewer.scene.camera.pickEllipsoid(movement.endPosition, viewer.scene.globe.ellipsoid);
        if (positions.length >= 2) {
            if (!Cesium.defined(poly)) {
                poly = new PolyLinePrimitive(positions);
            } else {
                positions.pop();
                // cartesian.y += (1 + Math.random());
                positions.push(cartesian);
            }
            distance = getSpaceDistance(positions);
            // console.log("distance: " + distance);
            // tooltip.innerHTML='<p>'+distance+'米</p>';
        }
    }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);

    handler.setInputAction(function (movement) {
        // tooltip.style.display = "none";
        // cartesian = viewer.scene.camera.pickEllipsoid(movement.position, viewer.scene.globe.ellipsoid);
        // cartesian = viewer.scene.pickPosition(movement.position);
        let ray = viewer.camera.getPickRay(movement.position);
        cartesian = viewer.scene.globe.pick(ray, viewer.scene);
        if (positions.length == 0) {
            positions.push(cartesian.clone());
        }
        positions.push(cartesian);
        //在三维场景中添加Label
        //   var cartographic = Cesium.Cartographic.fromCartesian(cartesian);
        var textDisance = distance + "米";
        // console.log(textDisance + ",lng:" + cartographic.longitude/Math.PI*180.0);
        floatingPoint = viewer.entities.add({
            name: '空间直线距离',
            // position: Cesium.Cartesian3.fromDegrees(cartographic.longitude / Math.PI * 180, cartographic.latitude / Math.PI * 180,cartographic.height),
            position: positions[positions.length - 1],
            point: {
                pixelSize: 5,
                color: Cesium.Color.RED,
                outlineColor: Cesium.Color.WHITE,
                outlineWidth: 2,
            },
            label: {
                text: textDisance,
                font: '18px sans-serif',
                fillColor: Cesium.Color.GOLD,
                style: Cesium.LabelStyle.FILL_AND_OUTLINE,
                outlineWidth: 2,
                verticalOrigin: Cesium.VerticalOrigin.BOTTOM,
                pixelOffset: new Cesium.Cartesian2(20, -20),
            }
        });
    }, Cesium.ScreenSpaceEventType.LEFT_CLICK);

    handler.setInputAction(function (movement) {
        handler.destroy(); //关闭事件句柄
        positions.pop(); //最后一个点无效
        // viewer.entities.remove(floatingPoint);
        // tooltip.style.display = "none";

    }, Cesium.ScreenSpaceEventType.RIGHT_CLICK);

    var PolyLinePrimitive = (function () {
        function _(positions) {
            this.options = {
                name: '直线',
                polyline: {
                    show: true,
                    positions: [],
                    material: Cesium.Color.CHARTREUSE,
                    width: 10,
                    clampToGround: true
                }
            };
            this.positions = positions;
            this._init();
        }

        _.prototype._init = function () {
            var _self = this;
            var _update = function () {
                return _self.positions;
            };
            //实时更新polyline.positions
            this.options.polyline.positions = new Cesium.CallbackProperty(_update, false);
            viewer.entities.add(this.options);
        };

        return _;
    })();

    //空间两点距离计算函数
    function getSpaceDistance(positions) {
        var distance = 0;
        for (var i = 0; i < positions.length - 1; i++) {

            var point1cartographic = Cesium.Cartographic.fromCartesian(positions[i]);
            var point2cartographic = Cesium.Cartographic.fromCartesian(positions[i + 1]);
            /**根据经纬度计算出距离**/
            var geodesic = new Cesium.EllipsoidGeodesic();
            geodesic.setEndPoints(point1cartographic, point2cartographic);
            var s = geodesic.surfaceDistance;
            //console.log(Math.sqrt(Math.pow(distance, 2) + Math.pow(endheight, 2)));
            //返回两点之间的距离
            s = Math.sqrt(Math.pow(s, 2) + Math.pow(point2cartographic.height - point1cartographic.height, 2));
            distance = distance + s;
        }
        return distance.toFixed(2);
    }
}